As computers become faster and more powerful, and network bandwidth between computers increases, computer-based interfaces are becoming an increasingly central part of how people communicate. The now ubiquitous Windows/Icons/Mouse-Pointer (i.e., WIMP) paradigm was originally designed primarily for single-use. This paradigm results in serious inefficiencies in interaction, since the user can use the mouse to point to only a single location at one time. In contrast, multitouch interfaces allow their user to employ all fingers and both hands at the same time. Note that many interfaces which historically predate the computer have been multitouch (i.e., have involved varied and flexible simultaneous use of multiple fingers on both hands), such as musical instruments (e.g., the piano and guitar), industrial manufacturing equipment, and human driven vehicles such as automobiles and airplanes.
Lee (Lee, S. K., Buxton, W. and Smith, K. C., “A Multi-Touch Three Dimensional Touch-Sensitive Tablet” in Proceedings of CHI '85 (April 1985), ACM/SIGCHI, NY, 1985, pp. 21-25, incorporated by reference herein) and Han et al. (Han, J., “Bi-manual, multi-point, and multi-user interactions on a graphical interaction surface,” incorporated by reference herein) and others have demonstrated that computer interfaces based on multitouch devices—devices that can track the position and the time of concurrent touch events upon a surface by multiple fingers and hands—and have shown the utility of such devices through a variety of applications.
In order for such devices to find themselves in widespread use, they need to be inexpensive and robust (i.e., not susceptible to signal error, and capable of operating properly in a variety of operating environments). It is also useful for such devices to be scalable to large size, and not at prohibitive expense, since multitouch interfaces are particularly useful for multi-person interaction, which becomes practical only at large sizes (e.g., the size of a whiteboard, as opposed to the size of a standard notebook computer). It is also desirable, both for reasons of economy of construction and simplicity of operation, for the touch surface itself to be a passive element, rather than an active electronic component. In addition, it is desirable to be able to assemble an arbitrarily large touch surface simply by placing together adjacent sections.
The current invention satisfies all these conditions. It is able to detect multitouch events upon a surface with high quality (high speed and very high signal to noise ratio). The multitouch surface itself is a passive element, which is already manufactured in large quantities and sizes at low cost. All other elements of the device are inexpensive and commercially available.
It is also possible to use the current invention in ways that are not possible with previous methods. For example, the method can be used to create a two-sided touch wall, which also functions as a front and rear projection display wall. Different users can simultaneously touch both faces of this wall, and the system will be able to simultaneously and independently track multitouch events upon both faces of the wall. This capability creates new opportunities for collaborative interfaces, not possible with previously known multitouch techniques.